Reconstruction of Severe Acetabular Bone Defects Using a Multi-cup Technique in Revision and Complex Primary Total Hip Arthroplasty

Objective: This study aimed to report the mid- to long-term clinical and radiographic outcomes of the multi-cup technique for treating severe acetabular bone defects in revision and complex primary total hip arthroplasty. Methods: A retrospective review was conducted on 26 patients (28 hips) who underwent revision total hip arthroplasty (THA) using the multi-cup technique from 2014 to 2023. According to the Paprosky classification, the acetabular defects were type IIC 8 case, type IIIA 11cases and type IIIB 9 cases (3 cases with pelvic discontinuity). Based on the number of the acetabular cups. The patients were divided into the double-cup and triple-cup group. Patients were followed clinically and radiographically for a mean of 6 Years. Results: T he mean Harris Hip Score (HHS) improved from 32.0 preoperatively to 86.3 at the last follow-up. The Merle d’Aubigné-Postel scores for pain and walking improved from 2.6 to 5.3 and from 2.2 to 4.1, respectively. Compared with the contralateral side, The mean superior displacement of the hip centre of rotation (COR) was corrected from 36.5 mm pre-operatively to 0.3 mm post-operatively. Similarly, the mean post-operative medial displacement was corrected from 8.9 mm to 1.4 mm. Furthermore, the efficacy of correcting COR(upward/downward and inward/outward displacement) in the triple-cup group was superior to the double-cup group(p < 0.05). Two patients of triple-cup group experienced a dislocation three weeks and three months post-operatively, respectively; One patients of double-cup group experienced an intra-operative Vancouver type B2 periprosthetic femoral fracture,and periprosthesis joint injection, respectively. Three patients exhibited a non-progressive radiolucent line in the acetabular zone C, which remained stable at the last follow-up. All patients showed no evidence of component migration or loosening. Conclusion: The multi-cup technique can be a viable alternative for severe bone defects in revision and complex primary THA which resulted in acceptable clinical and radiographic outcomes at the mid- to long-term follow-up. Compared with the double-cup technique, the triple-cup technique showed advantage in restoring the hip COR but disadvantage in dislocation.